QmakeProject: Fix crash on unloading project while parsing

Callign applyAsyncEvaluate in the desctructor might lead to further
parses, which we don't want. So bail out early in applyAsyncEvaluate.

Task-number: QTCREATORBUG-13421
Change-Id: I776ff477363a3985ebc26e9160c58c2ab9c910b7
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/qmakeprojectmanager/qmakeproject.cpp

@@ -1675,6 +1675,11 @@ ProjectImporter *QmakeProject::createProjectImporter() const
     return new QmakeProjectImporter(projectFilePath().toString());
 }
 
+QmakeProject::AsyncUpdateState QmakeProject::asyncUpdateState() const
+{
+    return m_asyncUpdateState;
+}
+
 } // namespace QmakeProjectManager
 
 #include "qmakeproject.moc"